kernel 3.15.0-0.rc5.git0.1.fc21.x86_64 btrfs-progs 3.14 /dev/sdb2 = existing btrfs fs /dev/sdc3 = unformatted partition # btrfstune -S1 /dev/sdb2 # mount /dev/sdb2 /mnt mount: /dev/sdb2 is write-protected, mounting read-only # btrfs device add /dev/sdc3 /mnt Performing full device TRIM (75.90GiB) ... # btrfs fi show Label: 'rawhide' uuid: d372e5d1-386f-460c-b036-611469e0155e Total devices 1 FS bytes used 7.55GiB devid 1 size 79.31GiB used 11.04GiB path /dev/sda3 btrfs: utils.c:1769: get_fs_info: Assertion `!(ndevs >= fi_args->num_devices)' failed. Nothing listed in dmesg.-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html